JPH07232919A - Production of fine zinc oxide particles - Google Patents

Abstract

PURPOSE:To obtain fine zinc oxide particles whose particle diameter, particle shape, flocculated state and surface state have highly been controlled by heating a mixture of zinc (compd.) with a carboxyl group-contg. compd. and alcohol. CONSTITUTION:A mixture is prepd. by mixing 0.1-95wt.% (expressed in terms of ZnO) zinc (compd.) with 0.5-50 times (mol) as much carboxyl group-contg. compd. as Zn atoms and 1-100 times (mol) as much alcohol as Zn atoms or further adding a compd. contg. at least one kind of atomic group selected from among carboxyl, amino and amido groups, an imido bond, imido and ureido groups, a ureirene bond, isocyanato and urethane groups, etc., by the number of >=1 in one molecule. The carboxyl group-contg. compd. is based on satd. fatty acid having <=200 deg.C b.p. under atmospheric pressure. The mixture is heated to >=100 deg.C to obtain the objective fine zinc oxide particles having 0.005-10mum average particle diameter of primary particles.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a vulcanization accelerator for rubber,
Used as a raw material or additive for various paints, printing inks, paints, glass, catalysts, pharmaceuticals, pigments, ferrites, etc., as well as electrophotographic photoreceptors, printing materials, plate-making materials, UV shielding materials, UV absorbing materials, gas sensors, etc. The present invention relates to a method for producing zinc oxide fine particles that can be used for Further, the present invention relates to a method for producing zinc oxide fine particles useful as a raw material for coating agents, paints / resin additives, etc., as a so-called transparent / ultraviolet absorber having a high translucency in the visible range and a high ability to absorb ultraviolet rays.

[0002]

2. Description of the Related Art Conventionally, zinc oxide fine particles, so-called zinc white, are (1) a method for vapor phase oxidation of zinc vapor (French method,
(American method), or (2) a method in which a zinc salt and an alkali metal carbonate are reacted in an aqueous solution, washed with water, dried to obtain zinc carbonate powder, and then thermally decomposed in air. The zinc oxide obtained by the method (1) is said to have a submicron particle size, but since it is strongly secondary agglomerated during the manufacturing process, it requires a great deal of mechanical effort to disperse it in a paint or resin. In addition to that, a homogeneous dispersion state cannot be obtained. In addition, the method (2) can obtain a finer particle size (primary particle size) of 0.1 μm or less as compared with the method (1), but the cohesive force between the primary particles is strong and the particle size is small. The effect based on the particle size cannot be sufficiently obtained. Furthermore, it is impossible to obtain zinc oxide fine particles in which the morphology such as the particle diameter, particle shape, surface state and dispersion / aggregation state of the primary particles is strictly controlled according to the purpose of use by these methods. The current situation.

In recent years, as a material capable of absorbing ultraviolet rays, which is excellent in weather resistance and heat resistance and excellent in transparency in the visible range, that is, a so-called transparent / ultraviolet absorber, the particle diameter is substantially 0.
Development of zinc oxide fine particles of 1 μm or less is desired. As a method for producing the fine particles, in addition to (3) a method of vapor phase oxidation of zinc vapor, (4) a hydrolysis method of an alkali salt solution of a zinc salt (JP-A-4-164813 and JP-A-4-3-4).
57114, etc.), a method of further oxidizing the zinc sulfide obtained by autoclave treatment using a mixed solution of an acidic salt of zinc and ammonium acetate and hydrogen sulfide as a starting material (JP-A-2-311314). Wet methods have been proposed. The fine particles obtained by the method (3) are powders that are strongly secondary-aggregated as described above, and for the purpose of imparting ultraviolet absorbing ability or improving weather resistance, plastic molded products such as fibers, plates, films or coatings. Even if it is blended with the above, it is not possible to obtain a transparent product. Further, for the purpose of imparting ultraviolet absorbing ability to glass, plastic film, etc., the powder may be dispersed in an appropriate solvent and, if necessary, a binder resin may be mixed and applied to these transparent substrates as a coating agent. However, there is a problem that only a film having insufficient transparency and homogeneity can be obtained. On the other hand, in the method (4), not only the manufacturing process is complicated, but also the ultrafine particles obtained therefor are inevitably expensive. As described above, there is no known method for producing zinc oxide fine particles which can exhibit the functions and characteristics of the fine particles sufficiently and are highly versatile.

[0004]

DISCLOSURE OF THE INVENTION As a result of intensive studies in view of the above problems, the present inventors have found a novel and highly productive process for producing zinc oxide fine particles. That is, the present invention has been made to solve the above problems, by heating a mixture of zinc or a compound thereof, a carboxyl group-containing compound and an alcohol,
An object of the present invention is to provide a process for producing zinc oxide fine particles, which has a controlled particle diameter, particle shape, surface state, and the like, and whose degree of dispersion / aggregation is high, with high productivity. A further object of the present invention is to provide an industrial production method of zinc oxide fine particles, which can sufficiently exhibit the functions and characteristics as fine particles excellent in transparency and the like in use.

[0005]

The method for producing fine zinc oxide particles according to the present invention is characterized by heating a mixture of zinc or a compound thereof, a carboxyl group-containing compound and an alcohol. The zinc oxide fine particles produced by the production method of the present invention are characterized by being zinc oxide fine particles whose particle diameter is controlled in an arbitrary range and whose shape and dispersion state are freely controlled.

The present invention will be described in detail below.

The zinc oxide fine particles referred to in the present invention contain zinc atoms and oxygen atoms as essential components and contain 60% by weight or more of ZnO. Hexagonal (wurtzite type structure), cubic (salt type structure), cubic Crystal-centered structure means any one showing an X-ray diffraction pattern. Therefore, within the above range, for example, fine particles in which a metal element other than zinc such as an alkali metal or an alkaline earth metal is complexed with zinc oxide crystals as an atom or an ion, an oxide of a metal element other than zinc, and water. Fine particles in which inorganic compounds such as oxides, sulfides, nitrides, carbides and carbonates are dissolved in zinc oxide crystals, coupling agents such as silane coupling agents and aluminum coupling agents, or organosiloxanes, chelate compounds Organometallic compounds such as, fine particles formed by bonding to the surface of the zinc oxide crystal or forming a coating layer on the surface, halogen element, sulfate radical,
Particles in which an inorganic acid such as nitrate or an organic compound such as fatty acid, alcohol, amine are contained inside and / or on the surface of the particles are also included.

The size of the zinc oxide fine particles obtained by the production method of the present invention is not particularly limited, but the average particle diameter of the primary particles of the obtained fine particles is 0.005 to 10 μm, and particularly the average particle diameter of the primary particles. Can be produced by a simple process which has not been heretofore used, since zinc oxide fine particles having a controlled range of 0.005 to 0.1 μm and excellent dispersibility can be produced.

The zinc oxide fine particles obtained by the production method of the present invention are obtained as a zinc oxide fine particle dispersion containing 1 to 80% by weight in terms of zinc oxide. The zinc oxide fine particles are present in the dispersion as (a) a state in which the primary particles of the fine particles are highly dispersed without secondary aggregation, (b) a part of the primary particles of the fine particles, or Examples thereof include a state of secondary aggregation, (c) a state in which different particles containing dispersed primary particles of the fine particles are dispersed, and these are all included in the zinc oxide fine particle dispersion of the present invention. .

The zinc or its compound used in the raw material of the present invention is not limited as long as it is a compound containing zinc or a zinc atom, and among others, metallic zinc (zinc dust), zinc oxide (zinc white, etc.) , Zinc hydroxide, basic zinc carbonate, zinc acetate, zinc octylate, zinc stearate,
Zinc Oxalate Zinc lactate, zinc tartrate and zinc naphthenate are preferable in that the desalting step, which is essential in the conventional production method using raw materials such as zinc chloride, zinc nitrate and zinc sulfate, is unnecessary. Furthermore, metallic zinc (zinc dust), zinc oxide (zinc white), zinc hydroxide, basic zinc carbonate and zinc acetate are particularly preferable because they are inexpensive and easy to handle.

The carboxyl group-containing compound used as the raw material of the present invention includes all compounds containing at least one carboxyl group in the molecule. Specific examples of the compound include formic acid, acetic acid and propione. Acids, isobutyric acid, caproic acid, caprylic acid, lauric acid, myristic acid, palmitic acid, saturated fatty acids (saturated monocarboxylic acids) such as stearic acid, acrylic acid, methacrylic acid,
Unsaturated fatty acids (unsaturated monocarboxylic acids) such as crotonic acid, oleic acid and linolenic acid, saturated polycarboxylic acids such as oxalic acid, malonic acid, succinic acid, adipic acid, suberic acid, β, β-dimethylglutaric acid , Chain carboxylic acids such as unsaturated polycarboxylic acids such as maleic acid and fumaric acid, cyclic saturated carboxylic acids such as cyclohexanecarboxylic acid, aromatic monocarboxylic acids such as benzoic acid, phenylacetic acid and toluic acid, phthalic acid Aromatic carboxylic acids such as unsaturated polycarboxylic acids such as isophthalic acid, terephthalic acid, pyromellitic acid and trimellitic acid, carboxylic acid anhydrides such as acetic anhydride, maleic anhydride and pyromellitic acid anhydride, trifluoro Acetic acid, monochloroacetic acid, o-chlorobenzoic acid,
o-Nitrobenzoic acid, anthranilic acid, p-aminobenzoic acid, anisic acid (p-methoxybenzoic acid), toluic acid, lactic acid, salicylic acid (o-hydroxybenzoic acid), etc. Hydroxy group other than carboxyl group, amino Group, nitro group, alkoxy group, sulfonic acid group, cyano group, compound having functional group or atomic group such as halogen atom, acrylic acid homopolymer, acrylic acid-methyl methacrylate copolymer, etc. Examples thereof include polymers having carboxylic acid as at least one constituent element.

The carboxyl group-containing compound also includes carboxyl group-containing zinc compounds such as zinc carboxylates such as zinc acetate and zinc oxalate. When the zinc compound is used, the above-mentioned carboxyl group-containing compound is not necessarily used. It is not necessary to add the containing compound separately.

Alcohols used as raw materials in the present invention include aliphatic monohydric alcohols such as methanol, ethanol, isopropyl alcohol, n-butanol, t-butyl alcohol and stearyl alcohol,
Aliphatic unsaturated monohydric alcohols such as allyl alcohol, crotyl alcohol and propargyl alcohol, alicyclic monohydric alcohols such as cyclopentanol and cyclohexanol, aromatic compounds such as benzyl alcohol, cinnamyl alcohol and methylphenylcarbinol Heterocyclic monohydric alcohols such as monohydric alcohols and furfuryl alcohols 1
Polyhydric alcohols, ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, pinacol, diethylene glycol. , Glycol such as triethylene glycol, hydrobenzoin,
Aliphatic glycols having an aromatic ring such as benzpinacol and phthalyl alcohol, alicyclic glycols such as cyclopentane-1,2-diol, cyclohexane-1,2-diol and cyclohexane-1,4-diol, polyethylene Glycols such as polyoxyalkylene glycols such as glycol and polypropylene glycol, and monoethers and monoesters of the above glycols such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, triethylene glycol monomethyl ether, ethylene glycol monoacetate, and hydroquinone. , Resorcin, 2,2-bis (4-hydroxyphenyl) propane and other aromatic diols and their monoethers and monoesters, glycerin and other trihydric alcohols These monoethers, monoesters, diethers, the compounds of alcohols such as diesters may be used alone, or two or more may be used in combination.

The present invention comprises the above zinc or a compound thereof,
It is characterized in that a mixture (m) comprising the above-mentioned carboxyl group-containing compound and the above-mentioned alcohol is heated. The above zinc or its compound is converted into zinc oxide which is crystalline in X-ray diffraction by heating in a mixture (m) obtained by mixing the above carboxyl group-containing compound and the above alcohol. At the same time, a dispersion containing fine particles of zinc oxide is obtained. At this time, if any one of the three components of the zinc or the compound thereof, the carboxyl group-containing compound and the alcohol is lacking, the zinc oxide crystal precipitation reaction does not occur, and the zinc oxide fine particle dispersion cannot be obtained.

Further, zinc or a compound thereof may undergo one or more zinc oxide precursors in the process of being converted into zinc oxide which is X-ray diffraction crystalline. For example, there is a case where zinc oxide or the like is used for zinc or its compound. The zinc oxide precursor means a state of an ion or a compound containing at least a zinc atom other than zinc oxide, such as zinc (hydrate) ion (Zn ²⁺ ), polynuclear hydroxide ion of zinc, and zinc A state in which a part or all of the above ions are chelated by a β-dicarbonyl compound such as acetylacetone or a compound having a chelate forming property such as lactic acid, ethylene glycol, ethanolamine, or (basic) zinc acetate, ( Basic) zinc salicylate,
The case where it exists as a (basic) carboxylate such as (basic) zinc lactate is cited. A case where a part or all of the precursor is present as a composite composition such as a complex salt with a carboxyl group-containing compound and / or alcohol is also included.

In the process in which zinc or its compound in the mixture (m) is converted into zinc oxide fine particles, the carboxyl group-containing compound present in the mixture (m) is
Either unchanged or part or all of the compound undergoes an esterification reaction with part or all of the alcohol in the mixture (m) to form an ester compound.

The mixture (m) may be any one obtained by mixing the above zinc or its compound, the above carboxyl group-containing compound, and the above three components of alcohol as essential components, and if necessary, Components other than the three components, such as water, ketones, esters, (cyclo) paraffins, ethers, organic solvents such as aromatic compounds, components such as additives described below, or metal components other than zinc, such as metal It may contain inorganic salts such as acetate, nitrate and chloride, and organic metal alkoxides such as metal alkoxide.
These water and organic solvent are usually contained as solvent components.

The state of existence of the above three components and the form of existence of each component in the mixture (m) are not particularly limited. For example, if the presence state of zinc or a compound thereof is illustrated, alcohol or / and water and the organic solvent or the like are used as solvent components, and zinc or a compound thereof is dissolved as it is, and is converted into the zinc oxide precursor and dissolved. In this state, a colloidal state, a colloidal state, an emulsified state, or a suspended state is dispersed.

Therefore, the state of the mixture (m) is not particularly limited, and there is no problem even if it is in the form of liquid, sol, emulsion or suspension.

The raw material composition for preparing the mixture (m) is not particularly limited, but the amount of zinc or its compound used as the raw material of the mixture (m) is ZnO based on the total amount of the mixture (m). The amount of the carboxyl group-containing compound used as a raw material of the mixture (m) is in the range of 0.1 to 95% by weight, and the zinc atom used in the raw material of the mixture (m) or Zn atom in the compound. Expressed as a molar ratio to 0.5 to 50 times the molar range,
It is preferable from the viewpoints of economy, easiness of forming zinc oxide fine particles, etc., and it is usually carried out within this range.

The mixture (m) is within the above-mentioned range.
Each component is mixed and prepared. The preparation method is not particularly limited.

Particularly, the average particle size of the primary particles is 0.005 to 0.005.
In order to obtain a dispersion of zinc oxide fine particles controlled in the range of 10 μm, the mixture (n) consisting of the zinc or its compound and a carboxyl group-containing compound is added to an alcohol-containing solution under heating to obtain a mixture ( It is preferable to prepare m) in terms of obtaining practical productivity.

The preparation method at this time will be described below.

The method of adding the mixture (n) is, for example, a method of adding and mixing the mixture (n) all at once, or a method of mixing the mixture (n) by dropping it on or in the alcohol-containing solution, or A method of spraying the mixture (n) can be adopted.

The mixture (n) is added and mixed under normal pressure,
It may be carried out under pressure or under reduced pressure, but it is preferably carried out under normal pressure in view of manufacturing cost. When adding and mixing under normal pressure, when it is desired to obtain a zinc oxide fine particle dispersion that is highly uniform in particle diameter, shape, etc., and whose dispersed / aggregated state is controlled, an alcohol-containing solution is added during addition and mixing. 60
It is preferable to maintain the temperature of ℃ or more, especially 60 ℃ to 300 ℃. When the temperature of the alcohol-containing solution at the time of addition and mixing is less than 60 ° C., the viscosity of the mixture (m) may sharply increase during or after the addition and mixing, and the mixture may become a gel. In such a case, stirring may not be possible and uniform mixing may not be achieved, or heat transfer may be insufficient during the next step, that is, heating may induce a problem such as temperature distribution. It is difficult to obtain not only zinc oxide fine particles having a uniform particle diameter and particle shape, but also only aggregates. Such a problem is related to the zinc concentration in the mixture (m) and is more likely to occur when the zinc concentration is higher. Therefore, the lower limit temperature of these optimum temperatures differs depending on the pressure of the system, and when performing under reduced pressure or increased pressure,
It is necessary to appropriately select the temperature of the alcoholic solvent according to the pressure. This is not the case when it is desired to obtain a dispersion of agglomerated zinc oxide fine particles. As described above, when the mixture (n) is added while heating the alcohol-containing solution, a part of the carboxyl group-containing compound and / or a part of the alcohol in the mixture (m) is removed from the system by evaporation. Although it may be distilled off, the thus obtained product is also included in the mixture (m).

The raw material composition for preparing the mixture (n) is not particularly limited, but the amount of zinc or its compound used as the raw material of the mixture (n) is ZnO based on the total amount of the mixture (n). It is in the range of 1 to 90% by weight, and the amount of the carboxyl group-containing compound used as the raw material of the mixture (n) is 0.5 to 50 times in terms of the molar ratio to zinc atom in zinc or the compound. It is preferably in the molar range.

Mixture (n) prepared as described above
The mixture (m) is obtained by adding and mixing the above to the alcohol-containing solution.

When the mixture (n) is added and mixed, the mixture (n) may be at room temperature or in a heated state. In addition, it is particularly preferable that the alcohol-containing solution is agitated for the purpose of obtaining uniform mixing during the addition and mixing.

At this time, the content of the alcohol contained in the alcohol-containing solution is not particularly limited, but in order to carry out the reaction for producing zinc oxide fine particles during heating in a short time, it is contained in the mixture (m) of alcohols. It is preferably in the range of 1 to 100 times by mole in terms of molar ratio to Zn atom derived from zinc or its compound. The concentration of alcohol in the alcohol-containing solution is usually in the range of 5 to 100% by weight based on the total amount of the solution.

Mixture (m) obtained as described above
By heating, the dispersion containing zinc oxide fine particles can be obtained in good yield.

The heating temperature is not particularly limited, and it is needless to say that the heating temperature is higher than the temperature at which crystalline zinc oxide is deposited.
The particle size and shape of the zinc oxide particles to be finally obtained,
It is not uniquely determined according to the morphology such as dispersion / aggregation state, but it is necessary to select the heating temperature and the heating time from a comprehensive viewpoint including the initial composition of the mixture (m) and the various parameters described above. There is. In particular, in order to obtain a dispersion of zinc oxide fine particles in which the average particle size of primary particles is controlled in the range of 0.005 to 10 μm with practical productivity, 100 ° C. or higher, particularly 100 ° C. or higher and 300 ° C. or lower It is preferable to carry out at the heating temperature.

In this case, for example, the mixture (n) is added to 10
When the mixture (m) is obtained by adding and mixing to an alcohol-containing solution maintained at a temperature of 0 ° C. or higher, the temperature may be maintained as it is, or after heating or cooling to a predetermined temperature, heating is performed. May be processed. Moreover, when the mixture (n) is obtained by adding and mixing the mixture (n) to alcohol at a temperature lower than 100 ° C., the temperature may be raised to 100 ° C. or higher and then heat treatment may be performed. When the heating temperature of the mixture (m) is 100 ° C. or higher, it is easy to strictly control the composition of the reaction system including the rate and amount of evaporation and removal of excess or unnecessary components in order to obtain zinc oxide fine particles. Therefore, there is an advantage that it is easy to control the particle diameter of the fine particles obtained.

In the heating process for obtaining the dispersion, a part or all of the components other than the above-mentioned components, that is, alcohol, the ester compound produced by heating, or the solvent component present in the mixture as the case requires. May be removed by evaporation.

The heating time is not particularly limited, but is usually 0.1 hour to 30 times in order to complete the reaction.
Time is preferable.

When water is allowed to exist in the mixture (m), it is preferable that the free water concentration in the dispersion is such that it is converted into zinc oxide fine particles in the heating process. It is preferable to carry out the distillation until the content becomes 5% by weight or less, more preferably 1% by weight or less. The reason is that when the water concentration exceeds this range, the crystallinity of the zinc oxide fine particles becomes low and the function as zinc oxide cannot be sufficiently exhibited depending on the type of other components such as alcohol contained in the dispersion. This is because there are cases.

As the (final) composition in the produced zinc oxide fine particle dispersion, the amount of the carboxyl group-containing compound is based on the total amount of zinc atoms contained in the produced dispersion. It is preferably 0.5 times or less mol. The reason is that when the amount exceeds 0.5 times,
This is because the crystallinity of the zinc oxide fine particles may be lowered and the function as zinc oxide may not be sufficiently exhibited. Therefore, if the amount of the carboxyl group-containing compound present in the mixture (m) exceeds 0.5 times the total amount of zinc atoms contained in the produced dispersion in terms of zinc atoms, heating is performed. In the process, it is necessary to distill at least excess amount.
Of course, even if the above ratio is 0.5 times or less, the distillation may be carried out in the process of heating.

Further, for the purpose of controlling the particle diameter, particle shape, dispersed state or higher state of the primary particles of the finally obtained zinc oxide fine particles and / or controlling the polarity or composition of the fine particle surface, a specific addition is made. It is also possible for the agent to coexist in the process of heating. The addition timing of the additive is not particularly limited, and it may be either a step of preparing the mixture (m) or the mixture (n) or a step of heat treatment, and is appropriately selected depending on the purpose and the kind of the additive. For example, it is often preferable to add zinc oxide immediately before or immediately after the precipitation of zinc oxide crystals because the effect of the additive can be sufficiently exhibited.

In particular, in order to obtain zinc oxide fine particles which are highly uniform in particle size and particle shape of primary particles, carboxyl group, amino group, imino group, amide group, amide bond, imide group in the molecule. , Imide bond, ureido group, ureylene bond, isocyanato group, sulfonic acid group, sulfuric acid group, phosphoric acid group, metal hydroxyl group, metal alkoxy group, epoxy group,
A compound containing one or more atomic groups of at least one kind selected from the group consisting of a urethane group, a urethane bond and an ester bond, and / or a so-called chelating agent which forms a chelate compound by multidentate coordination with zinc ions. It is preferable that the (polydentate ligand) is used as an additive to coexist during the heat treatment.

Examples of the additive include long-chain saturated fatty acids such as caprylic acid, lauric acid, myristic acid, palmitic acid and stearic acid, and the above-mentioned carboxyl group-containing compounds and ester compounds thereof; monoethanolamine, Alcohols having primary, secondary, and tertiary amino groups such as diethanolamine and N, N-dimethylethanolamine, tetramethylammonium hydroxide, n
-Quaternary ammonium salt such as hexadecyltrimethylammonium hydroxide, 6-aminocaproic acid, N, N
Amino acids such as bis (octylaminoethyl) glycine, p-aminobenzoic acid, aspartic acid and glutamic acid, amino (di) carboxylic acids and their esters or anhydrides, 2-hydroxypyridine, pyridine-2,
Amino group-containing compounds such as pyridine derivatives such as 6-dicarboxylic acid and aliphatic amines such as octadecylamine and stearylamine; amides such as dimethylformamide, dimethylacetamide, benzamide, oxamide and oxamic acid; acid imides such as succinimide and phthalimide ,
Imino (di) carboxylic acids such as imino (di) acetic acid, imino group-containing compounds such as imino ethers; dicarboxylic acid ureides such as parabanic acid, alloxan, barbituric acid and dialuric acid, ureido acids such as oxalic acid and malonuric acid, uric acid And the like, β-aldehyde acid ureides such as uracil, ureido group-containing compounds and derivatives such as α-oxyacid ureido such as 5-methylhydantoin; urethane compounds such as ethyl carbamate and their N-nitrosides, N- Derivatives such as chloroacetylated compounds; isocyanato group-containing compounds such as tolylene diisocyanate, diisocyanyl diphenylmethane, hexamethylene diisocyanate, isobutyl isocyanate, and phenyl isocyanate; 1,2-epoxycyclohexene, 1,8-cineole, Ethylene glycol Cold diglycidyl ether, 1,
Aliphatic diglycidyl ethers such as 6-hexanediol diglycidyl ether, polyglycidyl ethers such as glycerol triglycidyl ether, pentaerythritol tetraglycidyl ether, and aliphatic and aromatic diglycidyl esters such as adipic acid diglycidyl ester In addition to the above, epoxy group-containing compounds such as resorcin diglycidyl ether, bisphenol A diglycidyl ether, and oligomers having an epoxy group as a functional group; methyltrimethoxysilane, phenyltrimethoxysilane, benzyltriethoxysilane, γ- Aminopropyltriethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimetho Silane coupling agents such as xysilane, γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, and stearyltrimethoxysilane, isopropyltriisostearoyl titanate, bis (dioctylpyrophosphate) oxyacetate titanate, tetraoctylbis (ditrityl) Various coupling agents such as titanate-based coupling agents such as decylphosphite) titanate and isopropyltri (N-aminoethylaminoethyl) titanate, aluminum-based coupling agents such as ethyl acetoacetate aluminum diisopropylate, and these Partial hydrolyzate; other than the above-mentioned coupling agent, for example, tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, diethoxydimethylsilane, Trimethylethoxysilane, hydroxyethyltriethoxysilane, tetraethoxytitanium, tetrabutoxytitanium, diethyldiethoxytitanium, tetrabutoxytitanium, tetramethoxyzirconium, tetrabutoxyzirconium, aluminum trimethoxide, aluminum tree n-butoxide, aluminum triisopropoxy. De,
Triethoxyborane, tri-n-butylborate, triethoxygallium, tri-n-butoxygallium, diethoxystrontium, hexaethoxytungsten,
Di-n-butoxy manganese, diisopropoxy cobalt, diethoxy nickel, di-n-butoxy nickel,
Triethoxy lanthanum, diethoxy barium, triethoxy yttrium, diethoxy copper, di-n-butoxy copper, pentaethoxy niobium, penta-n-butoxy niobium, pentaethoxy tantalum, penta-n-butoxy tantalum, triethoxy indium, tri- Organic metal compounds containing metal hydroxyl groups and / or metal alkoxy groups represented by metal alkoxides such as n-butoxyindium, tetraethoxytin, tetra-n-butoxytin, triethoxyiron, and tri-n-butoxyiron, and these Derivatives, and specific examples of the derivatives include (partial) hydrolyzates, oligomers, polymers and other condensates obtained by (partially) hydrolyzing and / or condensing these organometallic compounds alone or in a mixture. Trimethyl phosphate Triethyl phosphate, tributyl phosphate, tris (2-chloroethyl) phosphate, phosphoric acid ester such as (polyoxyethylene) bis [bis (2-chloroethyl) phosphate], methyl acid phosphate, propyl acid phosphate, lauryl acid phosphate, stearyl acid phosphate , Bis-2-ethylhexyl phosphate, diisodecyl phosphate and other acidic phosphoric acid esters, trimethyl phosphite and other phosphorous acid esters, dimethyldithiophosphoric acid, diisopropyldithiophosphoric acid and other thiophosphoric acid ester organic phosphorus compounds; at least 1 in the molecule Primary amino group, secondary amino group, tertiary amino group, 4
Organopolysiloxanes containing the above-mentioned atomic groups such as amino groups such as high-grade ammonio groups, carboxyl groups, sulfonic acid groups, phosphoric acid groups, hydroxyl groups, and epoxy groups; sodium lauryl sulfate, dodecylbenzenesulfonic acid (sodium), poly Anionic surfactants such as sodium oxyethylene lauryl ether sulfate, sodium dialkyl sulfosuccinate, calcium stearate, nonionic surfactants such as polyoxyethylene lauryl ether, polyoxyethylene alkylamine, polyethylene glycol monolaurate, glycerol monostearate Agents; cationic surfactants such as lauryl dimethylamine and stearyl trimethyl ammonium chloride, amphoteric surfactants such as lauryl betaine and stearyl amine acetate, etc. Various surfactants having a subgroup; (meth) acrylic polymer such as acrylic acid-methyl methacrylate copolymer, acrylamide-methyl methacrylate copolymer, polyurethane, polyester polymer, etc. At least one of the above atomic groups The polymer etc. which are contained are illustrated.

Further, as a so-called chelating agent (polydentate ligand) which forms a chelate compound by multidentate coordination with zinc ion, β-diketones such as acetylacetone, ethyl acetoacetate, benzoylacetone, ethylenediamine, Dimethylglyoxime, benzyldioxime, cyclohexane1,2-dionedioxime, dithizone, oxine, glycine, glycolic acid, oxalic acid, catechol, dipyridyl, 1,10-phenanthroline,
α-hydroxypropionic acid, monoethanolamine,
Examples include diethanolamine and ethylene glycol.

As described above, the size of the primary particles of the obtained zinc oxide fine particles depends on the kind and the amount of the additive,
The shape, the dispersed state of the primary particles, the higher-order structure, the surface polarity, the surface composition, etc. are greatly different. For example, composite oxide fine particles of the additive and zinc oxide fine particles or zinc oxide fine particles unique in the shape and / or higher order structure of primary particles may be obtained. As a specific example of the latter, when a polymer having the above-mentioned atomic group such as a carboxyl group or an amide group is used as an additive, fine composite particles in which zinc oxide fine particles are dispersed and contained in the polymer can be obtained. In this case, by selecting the kind of the polymer, the content of the atomic group, the molecular weight, the addition amount, etc., it is possible to obtain a unique composite fine particle in which zinc oxide fine particles are localized in the surface layer or a hollow fine composite particle. It is also possible to obtain fine particles with structural characteristics. In addition, for example, when a compound having a hydrophilic main chain such as methoxypoly (oxyethylene) monoglycolic acid is used as an additive, the size and shape of the primary particles are uniform, and it is 1 with respect to a polar solvent such as water. Zinc oxide fine particles having excellent dispersibility of secondary particles can be obtained. On the other hand, when a compound having a highly hydrophobic or lipophilic main chain such as alkyltrialkoxysilane and octadecylamine is used as an additive, It is possible to obtain zinc oxide fine particles having uniform size and shape and excellent in dispersibility of primary particles in a low polar solvent such as toluene or a nonpolar solvent.

The amount of the above-mentioned additive added is not particularly limited, but is usually 0.1% or more and 30% or less in terms of the weight ratio of the additive to zinc oxide contained in the zinc oxide fine particle dispersion. preferable. If it is less than 0.1%, the effect of adding the additive is not substantially seen, while if it exceeds 30%, zinc oxide may not be obtained.

The additives may be used alone or as a mixture, and the method of addition is not particularly limited, and may be appropriately selected depending on the type of additive, the timing of addition, and the like.
For example, when adding during heating, add the additives directly or
An example is a method of adding the one dissolved and / or diluted in an arbitrary solvent such as alcohol, but the latter method easily causes the additive to quickly diffuse in the reaction system and the addition effect is easily exhibited sufficiently. It is preferable in terms.

Next, in the above-mentioned present invention, a preferable embodiment for obtaining zinc oxide fine particles in which the average particle size of the primary particles is controlled in the range of 0.005 to 0.1 μm is particularly preferable. Among them, in particular (I)-
The conditions of (IV) are mentioned, Preferably (I)-(I
V) is two or three conditions, more preferably (I) to (IV) is to satisfy all the conditions.

The (I) zinc or its compound contains, as a main component, at least one selected from the group consisting of zinc oxide, zinc hydroxide and zinc acetate among the above zinc or its compounds, and particularly preferably. , Zinc oxide and /
Alternatively, it is mainly composed of zinc hydroxide.

The reason for this is that since zinc oxide, zinc hydroxide, and zinc acetate do not substantially contain impurities that hinder the reaction of forming zinc oxide fine particles in the heating process, 0.005 to 0. This is because it is easy to strictly control the particle size in a fine region of 1 μm. In particular, zinc oxide and zinc hydroxide are not only inexpensively available, but also the type of carboxyl group-containing compound can be arbitrarily selected. This is because the use of these raw materials makes it easy to obtain fine particles in the above-mentioned particle diameter range.

(II) The carboxyl group-containing compound is a saturated fatty acid having a boiling point of 200 ° C. or less at normal pressure.

Specifically, formic acid, acetic acid, propionic acid,
Butyric acid and isobutyric acid are preferred. The reason is that it is easy to control the content of the carboxyl group in the reaction system during the heating process from the preparation process of the mixture, and thus it is easy to strictly control the primary particle size in a fine region. Furthermore, it is preferable to use the saturated fatty acid in a ratio of 80 mol% or more in the total amount of the carboxyl group-containing compound.

The content of the carboxyl group-containing compound is not particularly limited as long as it falls within the above range, but the content of the carboxyl group-containing compound in the mixture (n) is zinc oxide. The range of 2.2 to 10 times by mole in terms of molar ratio with respect to Zn atom is particularly preferable in that fine particles with suppressed secondary aggregation and excellent in dispersibility can be obtained.

(Iii) As a method for preparing the mixture (m), the mixture (n) obtained by mixing the zinc or the compound thereof with the carboxyl group-containing compound is 100 ° C. or higher, preferably 100 ° C. or higher 300 It is to add dropwise continuously or intermittently to an alcohol-containing solution maintained at a temperature of ℃ or less.

In this case, the mixture (n) is preferably in liquid form, and it is further desirable that zinc or its compound and the carboxyl group-containing compound are compatible or dissolved in a solvent having a high compatibility therewith. As the solvent used for that purpose, zinc or a compound thereof and a carboxyl group-containing compound described below can be easily dissolved by heating from room temperature to about 100 ° C., and in addition, they are highly compatible with alcoholic solvents, , Alcohols, ketones and esters are preferable. The alcohols mentioned here include all of the above-mentioned alcohols.

(Iv) The heating temperature of the mixture (m) is 10
It is performed at 0 ° C or higher and 300 ° C or lower.

Further, the average particle size of the primary particles is 0.00
In the zinc oxide fine particles in the range of 5 to 0.1 μm, the particle size and shape of the primary particles are controlled more uniformly, the surface condition such as hydrophilicity / hydrophobicity is controlled, and the dispersion / aggregation state is controlled. An effective method for such is described below. Also in the preferable method for producing zinc oxide fine particles having an average particle diameter of the primary particles in the range of 0.005 to 0.1 μm, by using the above-mentioned additive in the same manner as described above, the shape of the primary particles, It is possible to obtain zinc oxide fine particles in which the dispersed state, higher-order structure, surface polarity, etc. of the secondary particles are controlled and complex fine particles in which the fine particles are dispersed and contained. Further, in the case of obtaining zinc oxide fine particles in which the particle size distribution of the primary particles is uniform, the average particle size is substantially in the above range, and the dispersibility in various solvents is excellent, zinc used as a raw material or its A compound having at least one selected from the group consisting of zinc oxide, zinc hydroxide and zinc acetate as a main component,
A method using a basic zinc carbonate and / or one containing a zinc salt of a carboxyl group-containing compound having a boiling point at atmospheric pressure higher than the heating temperature as an auxiliary component is preferably used. The ratio of the subcomponent to the main component is usually 0.01% or more and 20% or less in terms of atomic ratio of zinc in the component. If the proportion is less than 0.01%, the combined effect of subcomponents is insufficient, while if it exceeds 20%, zinc oxide may not be obtained.

As another method for obtaining zinc oxide fine particles in which the shape and particle size distribution of the primary particles are uniform and the dispersibility of the primary particles is excellent, carbonate ions and / or
Alternatively, a method of coexisting CO ₂ is also effective. For example,
Prior to and / or during the zinc oxide formation reaction in the heat treatment process, carbon dioxide gas is intermittently or continuously supplied into the mixture (m), such as urea and ammonium (hydrogen carbonate) heating conditions. Examples include a method of adding a compound that produces carbon dioxide or carbonate ion under the conditions.

Among the production methods of the present invention, particularly according to the above-mentioned production conditions, the average particle diameter of the primary particles is 0.005 to 0.
The alcohol and / or the ester compound and / or the organic solvent are used as a solvent in the range of 1 μm, in which the particle shape, the surface state, the dispersed / aggregated state, etc. are controlled and the zinc oxide concentration is in the range of 1 to 80% by weight. A dispersion of fine zinc oxide particles is obtained.

The dispersion of zinc oxide fine particles obtained in the present invention can be used as it is, but if necessary,
Zinc oxide fine particles powder, paint containing zinc oxide fine particles,
It can be easily converted into a dispersion or the like in which zinc oxide fine particles are dispersed in another solvent by solvent substitution.

As a method for obtaining the powder of zinc oxide fine particles obtained in the present invention, the dispersion is subjected to a commonly used method such as filtration, centrifugation, solvent evaporation or the like to separate the fine particles, and then dried. Alternatively, a method of firing may be adopted as needed. Among them, the powderization method by the solvent evaporation method using the vacuum flash evaporation device after performing the concentration operation of the dispersion as needed is a method in which the secondary agglomeration of the fine particles, which tends to occur in the drying process, is suppressed. Therefore, it is preferable as a powdering method of zinc oxide fine particles having excellent dispersibility.

As a method for obtaining a dispersion in which zinc oxide fine particles are dispersed in a solvent different from the dispersion containing the zinc oxide fine particles obtained in the present invention, the powder obtained after pulverization according to the above-mentioned method Is mixed with a solvent to be replaced such as water, and then a known method of dispersing by mechanical energy such as a ball mill, a sand mill, an ultrasonic homogenizer, or heating the dispersion to evaporate or distill part or all of the solvent in the dispersion. A so-called heating solvent replacement method in which the solvent to be replaced is mixed while being removed can be adopted. The solvent component constituting the dispersion is not particularly limited, and alcohols, aliphatic and aromatic carboxylic acid esters, ketones, ethers, ether esters, aliphatic and aromatic hydrocarbons, halogenated carbonized Organic solvents such as hydrogen, water, mineral oil, vegetable oil, wax oil, silicone oil, etc. are exemplified,
It may be appropriately selected according to the purpose of use.

As a method for obtaining the coating material containing the zinc oxide fine particles obtained in the present invention, a method of directly adding and mixing a binder solution to a dispersion or a powder obtained after pulverizing according to the above-mentioned method is used as a binder. Any conventionally known method such as adding and mixing with a solution can be adopted. The binder component of the binder solution is not particularly limited and includes, for example, (meth) acrylic, silicone, melamine, urethane, alkyd, phenol, epoxy, polyester or other thermoplastic or thermosetting synthetic resin, Organic binders such as synthetic rubbers such as ethylene-propylene copolymer rubber, polybutadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber or natural rubber; inorganic binders such as silica sol, alkali silicates, silicon alkoxides, phosphates, etc. Can be used.
Further, the solvent component of the above-mentioned dispersion may be used as the solvent component of the binder solution, and is appropriately selected according to the purpose, the kind of the binder and the like. Of course, additives such as pigments may be mixed in the paint depending on the purpose of use.

For example, for the purpose of using the above-mentioned coating material for ultraviolet absorption, a coating material in which zinc oxide fine particles having an average primary particle diameter of 0.1 μm or less, preferably 0.05 μm or less are dispersed according to the method of the present invention is used. After being prepared, the coating material is applied to a base material such as a film, a fiber, a PC, an acrylic resin plate, glass, etc., which is desired to be shielded from ultraviolet rays, and dried, so that the ultraviolet rays are substantially transparent in the visible light range. It is possible to form a coating film that effectively shields.

As a method for obtaining a polymer molded product such as a fiber, film, resin plate or the like in which the zinc oxide fine particles obtained by the present invention are dispersed and contained, a process of synthesizing these matrix components and / or after synthesizing them, It can be obtained by adding and mixing in the form of powder or dispersion of zinc oxide fine particles obtained according to the above-mentioned method.

For example, when the fine particles are dispersed in the polyester film, the fine particles are dispersed by allowing a dispersion of zinc oxide fine particles dispersed in a glycol component, which is one raw material of the polyester, to coexist during the polymerization reaction of the polyester. After obtaining the contained polyester polymer, a sheet,
Examples thereof include a method of molding into a film, a fiber, or the like, or a method of forming a desired shape after dispersing and containing fine particles of zinc oxide fine particles in a master pellet in a polyester pellet synthesized in advance.

[0063]

EXAMPLES The present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

Regarding the obtained zinc oxide fine particle dispersion,
The crystallinity, particle shape, primary particle diameter, dispersion / aggregation state, particle concentration, composition and other physical properties or physical property values of the contained fine particles were analyzed and evaluated by the following methods. If it is necessary to pulverize before analysis and evaluation, follow the procedure below.
After pulverization, the obtained powder was used as a measurement sample.

The powdered product was directly subjected to all the analyzes.

(Preparation Method of Powder Sample) The fine particles in the obtained dispersion are separated by centrifugation and then vacuum dried at 80 ° C. to completely remove volatile components to obtain fine particle powder. Was used as the powder sample.

(Crystallinity) It was evaluated by powder X-ray diffraction measurement.

(Particle shape) It was judged by a scanning electron microscope or a transmission electron microscope at a magnification of 10,000.

(Primary particle diameter) The particle diameter of 100 arbitrary particles in a scanning electron microscope image or a transmission electron microscope image of 10,000 times was measured and determined from the following formula. In the case of a scanning electron microscope image, the noble metal alloy is vapor-deposited prior to the measurement, but the value of the obtained particle size is larger than that of the transmission electron microscope image due to the thickness of the vapor-deposition layer. It was shown by the value after.

[0070]

[Equation 1]

(Dispersion / aggregation state) Evaluation was carried out by an optical microscope and a centrifugal sedimentation type particle size distribution measuring device. The evaluation criteria are as follows.

A: primary particles are dispersed, B: partial aggregation, C: aggregation (fine particle concentration in dispersion) A portion of the dispersion can be completely removed of volatile components such as a solvent at 100 ° C. Dry powder was obtained by vacuum drying until the weight fraction of the obtained powder with respect to the suspension was obtained, and this value was defined as the concentration of fine particles in the dispersion.

(Solvent Composition in Dispersion) The solvent in the dispersion was separated by centrifugation and identified and quantified by mass spectrometry and gas chromatography.

(Fine particle composition) A powder sample was subjected to elemental analysis, ion chromatography, infrared absorption spectrum, NMR, fluorescence X.
The line analysis, the atomic absorption analysis, the gravimetric analysis and the like were comprehensively determined.

Example 1 In a 10 L glass reactor equipped with a stirrer, a dropping port, a thermometer and a reflux condenser, 1.2 kg of acetic acid was mixed with 2.0 kg of methanol and 2.0 kg of deionized water. After the dissolution, 1.08 kg of zinc acetate dihydrate was added and mixed, and then the temperature was raised to 60 ° C. with stirring to obtain a zinc-containing solution (A1) as a uniform solution.

Next, a stirrer capable of heating the heat medium from the outside,
12 kg of benzyl alcohol was charged into a 20 L glass reactor equipped with a dropping port, a thermometer, and a distillate gas outlet, and the internal temperature was raised to 150 ° C. and maintained. To this, 60 ℃
6.28 kg of the zinc-containing solution (A1) held in was added dropwise over 30 minutes by a metering pump. The bottom temperature varied from 150 ° C to 138 ° C. After the dropping was completed, the internal temperature was raised to 200 ° C. and the temperature was maintained for 5 hours to obtain 5.80 kg of a white dispersion (D1). Dispersion (D1) was a dispersion in which crystalline zinc oxide fine particles having a primary particle diameter of 40 to 90 nm were considerably secondary aggregated and dispersed in a solvent containing benzyl alcohol as a main solvent. As a result of analyzing the composition of the dispersion (D1), the zinc oxide fine particle concentration was 7.0% by weight, the solvent component was benzyl alcohol 61.4% by weight, and the benzyl alcohol acetate ester was 31.6% by weight. . Table 2 shows the physical properties or physical properties of the dispersion (D1) and the zinc oxide fine particles contained in the dispersion.

Example 2 In the same glass reactor as used in Example 1, 0.3 kg of commercially available zinc oxide powder was added to and mixed with a mixed solvent of 1.5 kg of acetic acid and 1.5 kg of ion-exchanged water, followed by stirring. While heating up to 80 ° C., a zinc-containing solution (A2) as a uniform solution was obtained.

Next, a stirrer capable of heating the heat medium from the outside,
To a 20 L glass reactor equipped with a dropping port, a thermometer and a distillate gas outlet, 12 kg of 2-butoxyethanol was charged, and the internal temperature was raised to 150 ° C. and maintained. to this,
3.3 kg of zinc-containing solution (A2) kept at 80 ° C
Was added dropwise by a metering pump over 30 minutes. The bottom temperature varied from 150 ° C to 128 ° C. After the dropping was completed, the internal temperature was raised, and when it reached 160 ° C., 0.15 kg of a solution of 0.015 kg of lauric acid in 2-butoxyethanol was added and mixed, and after reaching 170 ° C., By holding the temperature for 4 hours, 9.9 kg of a milky white dispersion (D2) was obtained.

The dispersion (D2) has a primary particle diameter of 20 nm.
It was a dispersion in which crystalline zinc oxide fine particles having a uniform size were almost monodispersed. Table 2 shows the physical properties or physical properties of the dispersion (D2) and the zinc oxide fine particles contained in the dispersion.

Example 3 Table 1 shows reaction conditions such as kinds of raw materials, used amounts of raw materials, additives and the like.
A zinc oxide fine particle dispersion was obtained in the same manner as in Example 2 except that the change was made as shown in FIG. The obtained dispersion was concentrated by distilling off part of the solvent in the dispersion under reduced pressure using an evaporator at a temperature of 120 ° C., and then the concentration was adjusted using 2-butoxyethanol. By performing the above, a dispersion (D3) containing 10% by weight of zinc oxide fine particles was obtained. Table 2 shows the physical properties or physical properties of the dispersion (D3) and the zinc oxide fine particles contained in the dispersion.

Example 4 A zinc oxide fine particle dispersion was obtained in the same manner as in Example 2 except that the types of raw materials, the amounts of the raw materials used, the reaction conditions such as additives were changed as shown in Table 1. After concentrating the obtained dispersion by distilling off a part of the solvent in the dispersion under reduced pressure using an evaporator at a temperature of 120 ° C.,
By adjusting the concentration using 2-butoxyethanol, a dispersion containing 25% by weight of zinc oxide fine particles (D
4) was obtained. Table 2 shows the physical properties or physical property values of the dispersion (D4) and the zinc oxide fine particles contained in the dispersion.

Example 5 A zinc oxide fine particle dispersion (D5) was obtained in the same manner as in Example 1 except that the reaction conditions such as the type of raw material and the amount of raw material used were changed as shown in Table 1. Table 2 shows the physical properties or physical property values of the dispersion (D5) and the zinc oxide fine particles contained in the dispersion.

[0083]

[Table 1]

[0084]

[Table 2]

Example 6 The dispersion (D2) obtained in Example 2 was concentrated in the same manner as in Example 3 to obtain a concentrated dispersion (D6) having a zinc oxide concentration of 20% by weight, which was added with methanol. The powder raw material slurry (S
As 6), the powder was pulverized by the following method using a vacuum flash evaporation device.

A stainless steel long tube having an inner diameter of 8 mm and a length of 9 m was heated to 200 ° C. by passing pressurized steam through a jacket covering the stainless steel long tube. The powder raw material slurry (S6) was continuously fed from the supply port) with a metering pump at a flow rate of 10 kg / hr. The other end of the long tube is maintained at a constant decompression degree of 50 Torr and is connected to a bag filter for separating the powder and the evaporated solvent. The powder of zinc oxide fine particles (P6) separated there is , The same vacuum pressure of 50 Torr was collected in the powder collection chamber.

The obtained powder (P6) is easily dissolved in an aromatic hydrocarbon such as toluene, a ketone such as MEK, an ester such as butyl acetate, an organic solvent such as alcohols such as methanol and isopropyl alcohol. It was dispersed in the state of primary particles.

Example 7 Instead of lauric acid in Example 2, methyl methacrylate (MMA) -acrylic acid (AA) copolymer (MM
A / AA = 9/1 wt / wt, weight average molecular weight 7,50
0; hereinafter, abbreviated as MMA-AA polymer) 0.05
0.5-k 2-butoxyethanol solution containing 3 kg
A series of operations was performed in the same manner as in Example 2 except that g was added, and 3.4% by weight of spherical fine particles having an average particle diameter of 1.2 μm was added.
10.5 kg of a dispersion (D7) containing the product was obtained. Next, after removing the solvent from the dispersion (D7) by centrifugation,
By drying, spherical fine particle powder (P7) 0.3
4 kg was obtained. The spherical fine particle powder (P7) was composed of zinc oxide fine particles containing 88% by weight of zinc oxide and MMA.
-Compound composition of AA polymer and particle size 20
It was confirmed by transmission electron microscope observation, thermogravimetric analysis, X-ray diffraction measurement, and the like that the zinc oxide fine particles having a particle size of 10 nm were localized and dispersed in the outer shell layer. Also,
It was confirmed that the spherical fine particle powder (P7) was a fine particle having excellent dispersibility and effectively absorbing ultraviolet rays. Therefore, the spherical fine particle powder (P7) is a UV shielding filler useful as a raw material for coating paints or an additive that imparts UV shielding ability to various plastic films, molded products such as resin plates, glass and the like.

Comparative Example 1 A zinc-containing precursor (Z1) was prepared in the same manner as in Example 1 except that orthoxylene was used instead of benzyl alcohol in Example 1 after preparing a zinc-containing solution (A1). The body-containing solution was added dropwise to the heated orthoxylene,
Further, a suspension was obtained by heating and holding at 140 ° C. for 2 hours. As a result of X-ray diffraction measurement, the fine particles contained in the suspension were not zinc oxide fine particles.

Comparative Example 2 A zinc-containing solution (A2) was prepared in the same manner as in Example 2 except that ethylene glycol-n-butyl ether acetate was used instead of 2-butoxyethanol in Example 2. Similarly, the zinc oxide precursor-containing solution was added dropwise to heated ethylene glycol-n-butyl ether acetate, and the suspension was obtained by heating and holding at 170 ° C. for 2 hours. As a result of X-ray diffraction measurement, the fine particles contained in the suspension were not zinc oxide fine particles.

Reference Example 1 The dispersion (D2) obtained in Example 2 was concentrated in the same manner as in Example 3 and the concentration was adjusted with toluene to obtain a dispersion (D2-2) having a zinc oxide fine particle concentration of 10% by weight. Got A coating material having the following composition was prepared using the dispersion (D2-2).

Coating composition: Dispersion (D2-2) 100 parts by weight Aroset 5247 200 parts by weight (manufactured by Nippon Shokubai Co., Ltd., solid content 45% by weight) Toluene 100 parts by weight The coating material was applied to a glass plate using a bar coater, A coating film was obtained by applying it to each substrate such as a polyester film and an acrylic plate and drying. When applied to any of the substrates, the obtained coating film was excellent in light transmittance in the visible range and effectively cuts ultraviolet rays. Table 3 shows the results of measuring the spectral transmittance of the glass plate having the coating film (thickness 11 μm) formed on the glass plate.

Reference Comparative Example 1 In Reference Example 1, zinc oxide fine particles (average particle diameter of primary particles: 0.04 μm) obtained by the French method were used instead of the dispersion (D2). A coating material having a zinc oxide concentration of 10% by weight was prepared in the same manner as in Reference Example 1, and a coating film (thickness 10 μm) was formed on a glass plate. The coating film had lower transparency and a lower UV cut rate than the coating film obtained in Reference Example 1. Table 3 shows the spectral transmittance of the glass plate having the coating film formed thereon.

[0094]

[Table 3]

Reference Example 2 After obtaining a dispersion (D2-2) in the same manner as in Reference Example 1, a coating material having the following composition was prepared using the dispersion (D2-2).

Coating composition: Dispersion (D2-2) 100 parts by weight Silica sol 120 parts by weight (OSCAL1432 manufactured by Catalysts & Chemicals Industry Co., Ltd.) Isopropyl alcohol 100 parts by weight The coating material was applied to a glass plate using a bar coater and dried. After that, a coating film was obtained. The obtained coating film was a film that was excellent in transparency in the visible light range but effectively absorbed ultraviolet rays and was excellent in scratch resistance.

Reference Example 3 10 parts by weight of the powder (P6) obtained in Example 6 and 500 parts by weight of polycarbonate resin pellets were mixed and melt-kneaded to melt the zinc oxide fine particles uniformly dispersed in an amount of 2% by weight. A polycarbonate plate having a thickness of 2 mm and a polycarbonate plate (A) were obtained by subjecting the product to extrusion molding. Obtained polycarbonate plate (A)
Has excellent light transmittance in the visible range, and also effectively blocks ultraviolet rays.

Reference Example 4 From the dispersion (D2) obtained in Example 2 to the dispersion (D2)
The solvent contained therein was removed by a centrifugation operation. The obtained zinc oxide fine particles containing a small amount of solvent were dispersed in methyl methacrylate (hereinafter abbreviated as MMA),
Centrifuged again. After this operation was repeated several times, the zinc oxide fine particles were dispersed in MMA to obtain 50 parts by weight of an MMA dispersion containing 20% by weight of zinc oxide fine particles.

Next, 0.4 part by weight of the polymerization initiator V-65 was added to 50 parts by weight of the MMA dispersion, and then added and mixed with 200 parts by weight of an aqueous solution containing 5% by weight of POVAL (PVA205 manufactured by Kuraray Co., Ltd.). After stirring for 5 minutes, a suspension containing zinc oxide fine particle-containing MMA as a dispersoid was obtained by a disperser.

The suspension was charged into a glass container equipped with a stirrer, a reflux condenser, and a thermometer, and the temperature of the liquid was raised to 70 ° C. and kept for 30 minutes while stirring, and then gradually raised. However, by finally holding the mixture at 95 ° C. or higher for 3 hours, the MMA polymerization reaction was carried out to obtain an aqueous suspension of zinc oxide fine particle-containing polymethylmethacrylate (hereinafter abbreviated as PMMA) particles. After centrifugation and washing with water were repeated several times, the suspension was dried at 60 ° C. to obtain zinc oxide fine particle-containing PMMA particles. As a result of analysis, the particles were composite particles containing 18% by weight of zinc oxide and having zinc oxide fine particles uniformly dispersed in PMMA and having a particle diameter of 10 to 70 μm. The particles effectively block ultraviolet rays and are useful, for example, as a filler for cosmetics.

Reference Example 5 10 parts by weight of the powder (P6) obtained in Example 6 and 100 parts by weight of polyester resin pellets were mixed and melt-kneaded to form a polyester composition in which 5% by weight of zinc oxide fine particles were uniformly dispersed. After obtaining a product, it is formed into a sheet by extrusion and then further stretched to a thickness of 50μ.
A polyester film of m was obtained. The film was a film in which fine particles of zinc oxide were uniformly and highly dispersed, and was a substantially transparent film that effectively blocks ultraviolet rays.

Similarly, a polyester composition containing 5% by weight of zinc oxide fine particles was obtained and then melt-spun to obtain a polyester fiber. The fiber is
It was a fiber in which fine particles of zinc oxide were uniformly and highly dispersed, and it was a fiber that effectively cuts ultraviolet rays.

Reference Example 6 From the dispersion (D5) obtained in Example 5, the dispersion (D2)
The solvent contained therein was removed by a centrifugation operation. The obtained zinc oxide fine particles containing a small amount of the solvent were dispersed in ion-exchanged water and centrifuged again. After repeating this operation several times, the zinc oxide fine particles were dispersed in ion-exchanged water to obtain 50 parts by weight of an aqueous dispersion (D5-2) containing 20% by weight of zinc oxide fine particles.

The water dispersion (D5-2), acrylic emulsion (Nippon Shokubai Co., Ltd., Akuriset ^R ES-285)
A coating material is prepared by mixing E) as a binder resin, and the polyester fiber is dipped in the coating material and dried to give a basis weight of zinc oxide fine particles of 0.5 g / m ²
To obtain a polyester fiber. The fibers were fibers with improved lightfastness.

[0105]

EFFECTS OF THE INVENTION The production method of the present invention is based on specifying the type and composition of raw materials to be used, the method for preparing a mixture, the type of alcohol, the heating conditions and the type and amount of additives to be added if necessary. , (1) size and shape of primary particles, 1
The morphology of secondary particles such as dispersion / aggregation state and surface state can be controlled freely. (2) It is composed of an extremely simple process. (3) It is excellent in economic efficiency. (4) Required for various uses. According to the respective performances, the zinc oxide fine particles having a preferable morphology and product form can be produced at low cost.

Further, the zinc oxide fine particles having a primary particle diameter of 0.005 to 0.1 μm produced by the production method of the present invention have excellent dispersibility in various solvents and the particle diameter is controlled in an extremely fine region. As a transparent UV absorber, it can be provided at low cost. Further, when the zinc oxide fine particles produced by the production method of the present invention is used as an ultraviolet absorber, it is used by itself, or when it is contained in cosmetics, paints, films, fibers, transparent resin plates, glass or the like, or when surface-treated to these, It has an unprecedented effect that it has excellent light transmittance in the visible range, is not toxic, and has excellent ultraviolet resistance, weather resistance, light resistance, heat resistance, and durability.

Further, since the zinc oxide fine particles produced by the production method of the present invention are highly controlled in particle diameter, particle shape, agglomeration state, surface state, etc., if they are contained as a photoconductor for electrophotographic plate making, The photoconductor shows excellent photoconductor characteristics that could not be achieved with conventional zinc oxide fine particles, and it is possible to provide an electrophotographic plate-type photoconductor in an inexpensive process without post-processing the zinc oxide fine particles to be used. It plays.

Claims (7)

[Claims] 1. A method for producing zinc oxide fine particles, which comprises heating a mixture of zinc or a compound thereof, a carboxyl group-containing compound and an alcohol. 2. The method for producing zinc oxide fine particles according to claim 1, wherein a mixture of zinc or a compound thereof and a carboxyl group-containing compound is added to a heated alcohol-containing solution. 3. The method according to claim 1, wherein a mixture comprising zinc or a compound thereof and a carboxyl group-containing compound is added to an alcohol-containing solution maintained at a temperature of 60 ° C. or higher and then heated. A method for producing the zinc oxide fine particles described. 4. The method for producing zinc oxide fine particles according to claim 1, wherein the average particle diameter of the primary particles of the obtained zinc oxide fine particles is in the range of 0.005 to 10 μm. 5. The zinc or the compound thereof contains at least one selected from the group consisting of zinc oxide, zinc hydroxide and zinc acetate as a main component. 2. The method for producing zinc oxide fine particles according to item 1. 6. The oxidation according to any one of claims 1 to 5, wherein the carboxyalkyl group-containing compound contains a saturated fatty acid having a boiling point of 200 ° C. or less under normal pressure as a main component. Manufacturing method of zinc fine particles. 7. A mixture comprising zinc or a compound thereof, a carboxyl group-containing compound and an alcohol, and further having a carboxyl group, an amino group, an amide group, an imide bond, an imide group, a ureido group, a ureylene bond, an isocyanato group and a urethane in the molecule. A compound containing at least one atomic group selected from the group consisting of a group, a urethane bond, an ester bond, a sulfonic acid group, a sulfuric acid group, a phosphoric acid group, a metal hydroxyl group, a metal alkoxy group and an epoxy group. The method according to claim 1, wherein the method coexists.